Mass update of suppliers sites

Hi,

The rules for paying a lot of our supplier has been changed.  We have to modify the sites of all of them to put new payment mode.

Those suppliers are employee type.

Is there a way to to a mass update for those sites?

Or

Can we use open interface supplier sites to update old sites or to create new sites?

Or

How can we make the old sites Inactive so a new site could be created with appropriate values?

Need help!  Time is short!

Thanks!